Fluorination in semi-aromatic polyesters accessed by ring-opening copolymerization leads to accelerated degradation and allows recovery of aryl bound fluoride.

This Review surveys the properties and applications of the pentafluoroorthotellurate ("teflate", OTeF₅) ligand and highlights the syntheses of the known teflate-based compounds across the periodic table. Due to the accessibility to several useful teflate transfer reagents and its unique properties, including strong electron-withdrawing character, considerable steric bulk, and stability against oxidation, a variety of intriguing p-block and d-block species have been reported. These encompass highly reactive Lewis acids, versatile weakly coordinating anions, neutral and cationic noble gas compounds, and a wide number of transition metal complexes. The lower analogues of the pentafluoroorthochalcogenate group, OSeF₅ and OSF₅, are described as well, although fewer examples are known. Recent progress in the derivatization of the OTeF₅ group to cis- and trans-PhTeF₄O or trans-(C₆F₅)₂TeF₃O moieties is also discussed, opening pathways to exciting new research directions.

A one pot room temperature synthesis of thionyl tetrafluoride (SOF₄) from elemental fluorine (F₂) and thionyl fluoride (SOF₂) is reported. The selective decagram scale process (100 mmol) allows a quantitative preparation of SOF₄ with high purity. The solid‐state structure has also been elucidated and compared with the reported gas phase one. The use of this reagent for the formation of the emerging pentafluorooxosulfate [cat][OSF₅] anions led to the preparation of multiple ion‐pairs (cat=Ag, NEt₃Me, PPN, PPh₄) in different organic solvents. The SuFEx reservoir ability of this anion was studied and by tuning the solvent system, the reactivity of pure thionyl tetrafluoride was observed using Ag[OSF₅] in THF and acetone.